The present invention relates to a flywheel assembly, and particularly to a flywheel assembly comprising a first flywheel, a second flywheel, and a viscous damping mechanism located between the flywheels.
Compound flywheel assemblies for automobile engines are in current use. Such a flywheel assembly typically comprises first and second flywheels, with a viscous damping mechanism disposed between them, as disclosed in U.S. Pat. No. 4,739,866 for example.
FIG. 6 shows a flywheel assembly as described in the above-cited United States patent. This assembly comprises a first flywheel 60 which is connected to an engine crankshaft and a second flywheel 62 on which a clutch 61 is mounted. The second flywheel 62 is rotatably supported on a hub 60a formed in the center of the first flywheel 60 through a bearing 63. A viscous damping mechanism 64 is disposed between the first and second flywheels 60 and 62 and elastically interconnects them. The viscous damping mechanism 64 is composed of a drive plate 66, a driven plate 68 connected to the second flywheel 62 by rivets 67, and torsion springs 69 for elastically connecting the drive plate 66 and the driven plate 68. A viscous damper 70 is located between the drive plate 66 and the first flywheel 60.
Torque transmitted to the first flywheel 60 is transmitted then from the drive plate 66 to the driven plate 68 through the viscous damper 70 and the torsion springs 69. The torque is in turn transmitted from the second flywheel 62 to a transmission-side member through the clutch 61.
The viscous damper 70 is subject to gradual wear over prolonged use of the flywheel assembly. Since the life or vehicles such as trucks or buses employing this viscous damper is longer than that of the damper itself, the damper must be replaced or rebuilt in maintenance.
However, the drive plate 66, which contains the viscous damper, is fixed to the first flywheel 60 through rivets 65, which encumbers the performance of maintenance to the flywheel assembly. It is necessary, for example, to provide special equipment for reassembly, increasing maintenance costs.
Reassembly of the viscous damper mechanism 64 changes its axial clearances such that it is difficult to obtain consistency of the restored damping characteristics.
Wherein it is desirable to alter the damping characteristics to better suit the operating conditions or particular characteristics of vehicles into which the flywheel assembly is installed, it would become necessary to disassemble all related components and change the viscous damper or the torsion springs. However, such disassembly work is so troublesome that the whole flywheel assembly is simply replaced in order to change the damping characteristics.